JP4157286B2 - Press mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a press molding die , and more particularly, to a press molding die capable of increasing / decreasing the wrinkle pressing force in one molding process and further increasing / decreasing the wrinkle pressing force for each place. Is.
[0002]
[Prior art]
Conventionally, attempts have been made to suppress the occurrence of press molding defects by increasing or decreasing the wrinkle pressing force in one molding process. For example, as disclosed in Japanese Patent Laid-Open No. 02-37922, the wrinkle holding force is increased in one molding process to prevent the generation of wrinkles on the body, or disclosed in Japanese Patent Laid-Open No. 9-38728. As described above, there has been proposed a molding method for avoiding breakage by reducing the wrinkle holding force in one molding process.
[0003]
On the other hand, as a device for increasing / decreasing the wrinkle holding force in one molding process as described above, as disclosed in JP-A-10-76323 and JP-A-61-190316, an electromagnetic proportional relief valve or the like A method of installing a hydraulic or pneumatic circuit consisting of a control valve, a detecting device for detecting the pressing force at the stroke position of the press slide and a control device for electrically controlling the pressing force at an arbitrary stroke has been proposed. Yes.
[0004]
[Problems to be solved by the invention]
However, when the wrinkle pressing force control device as described above is installed, there is a problem that the press machine is large and expensive. In addition, even if the press machine is prepared to be large and expensive, it may be good to make a new one, but to assemble the wrinkle holding force control device in a press machine that is already in use, a major modification is required. Long-term facility shutdowns are required, which is almost impossible from a cost standpoint. Furthermore, the expensive wrinkle pressing force control device is not necessary for press molding of all the parts to be manufactured, and there is a great possibility that the investment efficiency is extremely deteriorated.
[0005]
The present invention has been made against the background of the above circumstances, and the object of the present invention is to devise the mold without using an expensive press machine having the wrinkle pressing force control device. It is an object of the present invention to provide a press mold that can increase and decrease the wrinkle pressing force and further increase and decrease the wrinkle pressing force for each place.
[0006]
[Means for Solving the Problems]
The invention of claim 1 has been made in order to achieve the object, placed punches, the die and the blank holder or Ranaru press molding die, a cylinder is a pressure generating unit of the hydraulic cam between the die and the blank holder The hydraulic cam pump is installed outside the crease holder and under the die, and a cylinder that pressurizes the hydraulic cam pump is installed at a position opposite to the die hydraulic cam pump. When the pressurizing cylinder installed in the cylinder comes into contact with the pump, the cylinder between the die and the wrinkle presser starts to pressurize, so that the wrinkle presser force can be reduced in one molding process. Is. In addition, as in claim 2, a pressure cylinder can be further arranged between the punch and the wrinkle retainer, and the wrinkle retainer force can be increased and decreased in one molding process. As described above, the wrinkle presser can be divided so that the wrinkle presser force can be increased or decreased for each place.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
First , a reference example will be described with reference to FIG. In FIG. 1, at the initial stage of molding, the workpiece is sandwiched between the die 1 and the wrinkle presser 2, and the wrinkle pressing force applied to the workpiece is applied by the cushion pin that is in contact with the wrinkle presser at the lower side. . When molding proceeds and the wrinkle presser 2 comes into contact with the pressurizing cylinder 5, the wrinkle presser force increases to a value obtained by adding the force applied by the pressurizing cylinder to the force applied by the cushion pin. At this time, the timing of increasing the wrinkle holding force is determined by considering the height position of the wrinkle presser at the start and end of molding and the height and stroke of the pressurizing cylinder 5, putting a spacer under the pressurizing cylinder 5, Adjust the installation position height of the pressurizing cylinder 5 by making a recess in the mold (punch 3 in the case of FIG. 1) and installing the pressurizing cylinder 5 in it. It is possible to set arbitrarily by adjusting the contact position of the presser 2. Furthermore, it is also possible to increase the wrinkle pressing force in multiple stages by arranging a plurality of pressure cylinders 5 and changing the contact timing with the wrinkle presser 2.
[0008]
The installation position on the plane perpendicular to the height direction of the pressurizing cylinder is set to 0.5 (dc + D) <L in order to avoid interference with the cushion pin, and the surface pressure applied to the work piece by the wrinkle holding force is set. In order to prevent non-uniformity, L ≦ 3 (dc + D) is set. Here, dc is the diameter of the cushion pin, D is the outer diameter of the pressure cylinder, and L is the distance between the center of the pressure generating device and the closest cushion pin.
The degree of increase in the wrinkle holding force can be adjusted by adjusting the load capacity of the cylinder to be installed or by selecting a cylinder having the required pressurization capacity.
[0009]
Next, the invention of claim 1 will be described with reference to FIG. In FIG. 2, at the initial stage of molding, the workpiece is sandwiched between the die 1 and the wrinkle presser 2, and the wrinkle pressing force applied to the workpiece is applied by the cushion pin that is in contact with the wrinkle presser at the lower side. . When the molding progresses and the pressurizing cylinder 9 embedded in the die comes into contact with the pump portion 7 of the hydraulic cam, the cylinder portion 6 of the hydraulic cam applies a force in a direction to widen the space between the die 1 and the wrinkle retainer 2, and wrinkles. The holding force decreases to the value obtained by subtracting the force from the pressurizing cylinder from the force from the cushion pin. At this time, the decrease timing of the wrinkle pressing force can be arbitrarily set by adjusting the contact position between the pump portion 7 of the hydraulic cam and the pressurizing cylinder 9 embedded in the die 1. Further, by arranging a plurality of hydraulic cams and changing the contact timing between the pump portion 7 of each hydraulic cam and the pressurizing cylinder 9 embedded in the die 1, it is possible to reduce the wrinkle holding force in multiple stages. . Further, the degree of reduction of the wrinkle holding force is adjusted by adjusting the load capacity of the pressurizing cylinder 9 installed in the die 1 and the cross-sectional area ratio of the hydraulic cam cylinder section 6 and the hydraulic section of the pump section 7 or by the required pressurization. This is made possible by selecting a hydraulic cam having the capacity cylinder and the required cross-sectional area ratio between the pump part and the cylinder part. Further, the installation position of the pump portion of the hydraulic cam is not essential in order to prevent nonuniform surface pressure, but it is preferably directly above the cushion pin as shown in FIG.
[0010]
Next, the invention of claim 2 will be described. By incorporating the mechanism of claim 1 and the reference example into one mold and further shifting the timing of increasing and decreasing the wrinkle pressing force, the wrinkle pressing force can be increased or decreased in one molding process. Furthermore, by incorporating two or more of both the mechanisms of claim 1 and the reference example, it is possible to repeatedly increase and decrease the wrinkle presser.
[0011]
Next, the invention of claim 3 will be described with reference to FIG. FIG. 3 is a plan view of a ¼ portion of a mold for obtaining a molded part of a square tube, as viewed from the surface where a workpiece is placed on the mold before molding, for example, as shown in FIG. The portion of the molded product of the wrinkle presser 2 that is in contact with the workpiece that forms the straight wall and corner portions is divided. And it becomes possible to increase / decrease wrinkle pressing force for every place by incorporating the mechanism as described in any one of Claims 1-3 in all or one part of a division | segmentation part. Naturally, if a plurality of mechanisms according to claim 1 or 2 are incorporated in one divided portion, the wrinkle pressing force can be increased, decreased and increased or decreased in multiple stages.
[0012]
By using any of the press dies described above, a press molding method is possible in which the wrinkle pressing force is increased or decreased in one molding process, and the wrinkle pressing force is increased or decreased for each place. This makes it possible to manufacture molded parts that could not be achieved by the conventional molding method with a constant wrinkle pressing force. For example, by reducing the wrinkle holding force before breaking and accelerating material inflow, avoiding breakage, increasing the wrinkle holding force at the timing of wrinkle generation, avoiding wrinkle generation, , To avoid breakage and to eliminate shape freezing failure.
[0013]
【Example】
Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 4 is a view showing a mold structure for obtaining the molded part shown in FIG. In FIG. 4, the portion of the molded product of the wrinkle presser 2 that is in contact with the workpiece that forms the straight wall and corner portions is divided. In the corner portion, after the molding starts, the pressing cylinder 9 embedded in the die 1 first contacts the hydraulic pump 7 and the hydraulic cylinder 6 starts to press the wrinkle holding force. The pressurizing cylinder 5 comes into contact with the wrinkle presser 2 and pressurization is started, so that the wrinkle presser force is increased. On the other hand, the straight side portion has a mechanism that the pressurization cylinder 5 comes into contact with the wrinkle presser 2 after the start of molding and pressurization is started, so that the wrinkle presser force is increased. By using such a mold, as shown in FIG. 6, it is possible to increase / decrease the wrinkle holding force in one molding process and change the change pattern of the wrinkle holding force at the corner and the right side. It was. From the viewpoint of improving moldability, the meaning of the example in FIG. 6 is as follows. For the corner portion, the initial wrinkle holding force is set high to suppress wrinkle generation, and then the wrinkle holding force is reduced to avoid breakage. Thereafter, the wrinkle holding force is increased immediately before the bottom dead center in order to eliminate the shape freezing failure. On the other hand, the wrinkle pressing force is increased immediately before the bottom dead center in order to eliminate the shape freezing defect for the straight side portion.
[0014]
【The invention's effect】
As described above, according to the present invention, it is possible to perform molding in which the wrinkle holding force is changed during one molding process without using an expensive press molding apparatus. As a result, it becomes possible to form difficult-to-form materials such as high tension steel and aluminum, and the weight reduction of automobiles can be achieved by expanding application of these materials.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the concept of a reference example.
FIG. 2 is a schematic diagram showing the concept of the invention of claim 1;
3 is a schematic diagram showing the concept of the invention of claim 3. FIG.
FIG. 4 is a view showing a mold structure according to an embodiment of the present invention.
FIG. 5 is a view showing a molded product obtained in an example of the present invention.
FIGS. 6A and 6B are diagrams showing a change pattern of the wrinkle pressing force realized by the embodiment, in which a is a change pattern of the wrinkle pressing force in the corner portion and b is the right side portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dice 2 Wrinkle presser 3 Punch 4 Cushion pin 5 Cylinder for pressurization 6 Cylinder part of hydraulic cam 7 Pump part of hydraulic cam 8 Stroke end block 9 Cylinder for pressurization W Work material

Claims (3)

In a press mold consisting of punches, dies and wrinkle holders, the cylinder that is the hydraulic cam pressure generator is installed between the dies and wrinkle holders, and the hydraulic cam pump is installed outside the wrinkle holders and under the dies. Then, a cylinder that pressurizes the hydraulic cam pump is installed at a position opposite to the die hydraulic cam pump. A press molding die characterized in that it is possible to reduce the wrinkle pressing force in one molding process by starting the pressurization of the cylinder. 2. A press mold according to claim 1, wherein a pressurizing cylinder is further arranged between the punch and the wrinkle presser, and the wrinkle presser force can be increased and decreased in one molding process. . 3. The press mold according to claim 2, wherein the wrinkle presser is divided so that the wrinkle presser force can be increased or decreased for each place.

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